Antigen-specific cellular immune responses are important in controlling recurrent herpes simplex virus (HSV) infection. CD4+ lymphocytes are enriched in recurrent herpetic lesions. HSV-specific CD4 + T cells are present in peripheral blood and HSV lesions. CD4 + depletion and impaired proliferative responses to HSV correlate with disease severity in immunosuppressed persons. The effector mechanisms and antigenic specificities of lesion CD4+ T cells are unknown and are the focus of the proposed studies. We have developed techniques for culturing T lymphocytes from recurrent cutaneous HSV-2 lesions and have derived 26 CD4+ T cell clones with HSV-specific proliferative responses. Some clones display viral- and HLA-restricted cytotoxicity for LCL targets and some have antiviral effects. We will examine the correlation of cytolytic, antiviral, lymphokine secretion profiles and antigenic specificity. Multiple lymphokines including gamma-interferon, lL-2, lL-3, and TNF- have activity against HSV. We propose measurement of lymphokine production by HSV-specific T cell clones in response to antigen. The molecular specificities of established clones will be determined; to date, clones reactive with the candidate vaccine components glycoproteins B, C, and D of HSV-2 have been identified. We propose further evaluation of lesion- derived T cell clones for proliferative and cytotoxic responses to these and other glycoproteins. Antigens recognized by additional HSV-2-specific clones have been mapped with HSV-1 x HSV-2 intertypic recombinant viruses (IRV). Three clones recognize a region of six open reading frames of the HSV-2 genome and, in all, at least four previously unknown T cell antigens have been mapped by this approach. Because deletion mutants and other engineered molecular reagents are more readily available for HSV-1 than HSV-2, we propose epitope mapping of further HSV-1 and HSV-2-specific CD4+ clones with IRV, and utilization of existing HSV-1 reagents to determine the HSV-1 T cell antigens. The cloning and expression of the cognate HSV-2 proteins will then be conducted for functional evaluation. Definition of the cytotoxic activity of lesion-infiltrating CD4 + lymphocytes in recurrent HSV, knowledge of the roles of viral glycoproteins and other viral proteins as targets of the CD4 + response, and study of lymphokine secretion profiles and antiviral effects will increase our understanding of the relationship between the immune response and HSV and assist in the design and evaluation of candidate vaccines.